commit 9356ec1516cae84837629ef19b7158c0e1155852
author Matt Arsenault <Matthew.Arsenault@amd.com> Thu Feb 02 10:14:36 2023 -0400
committer Matt Arsenault <arsenm2@gmail.com> Fri Mar 17 11:29:50 2023 -0400
tree 194d30e335ae96de28db55625e296e6516c2ce56
parent 0eac3c500406ad3a18a8c2829f71403056c6042f

CodeGen: Reorder case handling for is.fpclass legalization

Subnormal and zero checks can be combined into one, so move
the code closer to reduce the diff in a future change.

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 1406fec..f0a5b2e 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -7438,6 +7438,20 @@
                                        AsInt, SignBitC));
   }
 
+  if (FPClassTest PartialCheck = Mask & fcSubnormal) {
+    // issubnormal(V) ==> unsigned(abs(V) - 1) u< (all mantissa bits set)
+    // issubnormal(V) && V>0 ==> unsigned(V - 1) u< (all mantissa bits set)
+    auto V = (PartialCheck == fcPosSubnormal) ? AsInt : Abs;
+    auto OneC = MIRBuilder.buildConstant(IntTy, 1);
+    auto VMinusOne = MIRBuilder.buildSub(IntTy, V, OneC);
+    auto SubnormalRes =
+        MIRBuilder.buildICmp(CmpInst::Predicate::ICMP_ULT, DstTy, VMinusOne,
+                             MIRBuilder.buildConstant(IntTy, AllOneMantissa));
+    if (PartialCheck == fcNegSubnormal)
+      SubnormalRes = MIRBuilder.buildAnd(DstTy, SubnormalRes, Sign);
+    appendToRes(SubnormalRes);
+  }
+
   if (FPClassTest PartialCheck = Mask & fcInf) {
     if (PartialCheck == fcPosInf)
       appendToRes(MIRBuilder.buildICmp(CmpInst::Predicate::ICMP_EQ, DstTy,
@@ -7474,20 +7488,6 @@
     }
   }
 
-  if (FPClassTest PartialCheck = Mask & fcSubnormal) {
-    // issubnormal(V) ==> unsigned(abs(V) - 1) u< (all mantissa bits set)
-    // issubnormal(V) && V>0 ==> unsigned(V - 1) u< (all mantissa bits set)
-    auto V = (PartialCheck == fcPosSubnormal) ? AsInt : Abs;
-    auto OneC = MIRBuilder.buildConstant(IntTy, 1);
-    auto VMinusOne = MIRBuilder.buildSub(IntTy, V, OneC);
-    auto SubnormalRes =
-        MIRBuilder.buildICmp(CmpInst::Predicate::ICMP_ULT, DstTy, VMinusOne,
-                             MIRBuilder.buildConstant(IntTy, AllOneMantissa));
-    if (PartialCheck == fcNegSubnormal)
-      SubnormalRes = MIRBuilder.buildAnd(DstTy, SubnormalRes, Sign);
-    appendToRes(SubnormalRes);
-  }
-
   if (FPClassTest PartialCheck = Mask & fcNormal) {
     // isnormal(V) ==> (0 u< exp u< max_exp) ==> (unsigned(exp-1) u<
     // (max_exp-1))